1. Field of the Invention
This invention relates to the casting of molten metals, and more particularly to the continuous vertical ascendant casting of metal components, such as cast iron pipes. Although the present invention applies to the casting of various types of metal components, it is particularly advantageous for the casting of thin-walled, cast iron pipes. The expression "thin-walled pipes" refers to pipes having a small thickness/diameter ratio, e.g., less than 10%, rather than the thickness considered by itself in isolation.
2. Description of the Related Art
The invention relates more specifically to a device for positioning a die block in a machine for the continuous vertical ascendant casting of cast iron pipes with respect to a vertical extraction axis. Such a casting machine incorporates a die block and a device for the supply of liquid iron which feeds the die block through the lower end thereof. Such a supply device is, for example, described in document FR-A-2 705 259 in the name of the Applicant. This device for the supply of liquid iron comprises a U-shaped siphon unit manufactured from cast refractory concrete, on which outlet the die block rests.
Given the high temperatures involved in the casting of molten metals, such a siphon unit becomes progressively worn and/or consumed by the molten iron which is in contact with it during the continuous casting process. In addition to this, when casting is stopped, solidification of the cast iron bursts the siphon unit.
As a consequence, this siphon unit must be replaced as a whole as soon as a particular number of pipes have been cast, i.e., is at every shut-down.
Given that the siphon unit is a relatively massive component, and given its location on the casting table of a casting machine in a pipe production system, in-situ replacement of the siphon unit is very difficult, if not impossible. For this reason, the entire casting table has to be removed from the pipe production system in order that it can be dismantled and the siphon easily replaced.
Furthermore, to shorten the length of the interruption in the manufacture of pipes several identical casting tables are used alternately. When a siphon unit on one of the casting tables has to be replaced, another is installed in the pipe manufacturing system.
However, when a casting table is replaced, alignment between the die and the vertical axis along which the pipes are extracted gives rise to a problem. In fact, the die block must be precisely aligned with the vertical extraction axis if the pipe manufacturing system to operate correctly. Now, given that the casting table has been completely dismantled, this alignment between the die block and the extraction axis is difficult and takes up a great deal of time, in particular on account of the uncertain geometry of the refractory material parts used.